NorovirusNorovirusControlling an OutbreakControlling an Outbreak

Melissa VaccaroMelissa Vaccaro

Program SpecialistProgram Specialist

PA Department of AgriculturePA Department of Agriculture

mvaccaro@state.pa.usmvaccaro@state.pa.us

NorovirusNorovirus

Bar = 50 nanometers

Single stranded, non-enveloped Single stranded, non-enveloped RNA virus belonging to the RNA virus belonging to the family family CaliciviridaeCaliciviridae

July 1997 to June 2000: 232 NoV outbreaks reported to CDC: 57% were foodborne, 16% were due to person-to-person spread, and 3% were waterborne; in 23% undetermined cause.

Source: CDC Norovirus Technical Fact Sheet. See http://www.cdc.gov/ncidod/dvrd/revb/gastro/norovirus-factsheet.htm

NoV NoV The Public Health ProblemThe Public Health Problem

Secondary Infections: Attack rate >50%Secondary Infections: Attack rate >50% in areas in areas where a large population is enclosed within a where a large population is enclosed within a static environment, such as: static environment, such as: institutions, institutions, schools, schools, military operations, military operations, hotels, hotels, recreational camps, or recreational camps, or aboard cruise ships aboard cruise ships

NoV NoV The Public Health ProblemThe Public Health Problem

NoV is the most common cause of NoV is the most common cause of gastroenteritis in people of all ages gastroenteritis in people of all ages Responsible for almost 50 % of all foodborne Responsible for almost 50 % of all foodborne gastroenteritis outbreaks and gastroenteritis outbreaks and 35% of all sporadic gastroenteritis outbreaks 35% of all sporadic gastroenteritis outbreaks Estimated to be as frequent a cause of illness Estimated to be as frequent a cause of illness and death internationally as and death internationally as Salmonella Salmonella foodborne illnessfoodborne illness The most significant diarrheal virus in terms of The most significant diarrheal virus in terms of work/education days lost because it impacts all work/education days lost because it impacts all agesages

Characteristics of NoVCharacteristics of NoV

Acute onset of vomiting (often explosive) and Acute onset of vomiting (often explosive) and diarrhea (also often explosive)diarrhea (also often explosive)Typically Lasts only 24 to 48 hours & rarely fatal, Typically Lasts only 24 to 48 hours & rarely fatal, Seasonal virus: Seasonal virus: Peaks in WinterPeaks in Winter (Dec.- March) (Dec.- March)Can have a serious impact on healthy Can have a serious impact on healthy individuals of all ages, resulting in hospitalization individuals of all ages, resulting in hospitalization and even intensive care, and and even intensive care, and Has been associated with serious complications Has been associated with serious complications or even fatalities in the elderly and immune or even fatalities in the elderly and immune compromised compromised

Potential Transmission LevelPotential Transmission LevelNorovirusNorovirus

Shed in the feces at levels up to Shed in the feces at levels up to 1 Trillion1 Trillion viral particles per gram of feces.viral particles per gram of feces.

One projectile vomiting incident can One projectile vomiting incident can potentially contaminate the environment potentially contaminate the environment with with 30,000,00030,000,000 viral particles. viral particles.

Infectious dose of NoV is now estimated to Infectious dose of NoV is now estimated to be as low as 1-10be as low as 1-10 viral particle (Teunis & viral particle (Teunis & Moe, 2008).Moe, 2008).

0

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500

1990 1993 1996 1999 2002 2005

Number ofNorovirusOutbreaks

Selected Published Foodborne Norovirus Outbreaks Associated with

Different SettingsMultiple

locations/ undetermined/other (11.1%)

Workplace, office setting

(10.7%)

Catered (15.8%)

Restaurant/deli (28.9%)

School (6.9%)

Cruise ship (6.8%)

Prison (0.35%)

Fair (1.1%)

Church; temple. etc. (2.7%)

Private home (7.3%)

Nursing home, etc. (9%)

Source of NoV Outbreaks Reported Source of NoV Outbreaks Reported to CDC (1991 – 2000) to CDC (1991 – 2000)

Of the 76 outbreaks Of the 76 outbreaks reported to CDC reported to CDC between 1991 to between 1991 to 2000 (for which data 2000 (for which data was complete and was complete and implicated foods), implicated foods), (Widdowson (Widdowson et alet al., ., 2005). 2005).

43%43% outbreaks outbreaks probably had some probably had some type of produce/fruittype of produce/fruit

Food ItemFood Item % of NoV % of NoV OutbreaksOutbreaks

SaladSalad 2626

Produce/fruitProduce/fruit 1717

SandwichesSandwiches 1313

Meat dishesMeat dishes 1111

Bakery Bakery productsproducts

77

Fish dishesFish dishes 55

OystersOysters 33

Risk of NoV Transmission Risk of NoV Transmission

Vomiting vs. Diarrhea: No Difference in Vomiting vs. Diarrhea: No Difference in risk of secondary transmission in the home risk of secondary transmission in the home vs a non home setting.vs a non home setting.

The more primary cases sick: the > The more primary cases sick: the > secondary illness ratesecondary illness rate

Transmission of NorovirusTransmission of NorovirusFecal-Oral RouteFecal-Oral Route: Primary route : Primary route responsible for causing foodborne responsible for causing foodborne outbreaksoutbreaksAirborne Inhalation of microscopic Airborne Inhalation of microscopic dropletsdroplets:: Aerosols enhance dissemination Aerosols enhance dissemination of NoV in the environment during an of NoV in the environment during an outbreak; has been important means of outbreak; has been important means of transmitting NoV to staff transmitting NoV to staff Person-to-PersonPerson-to-Person: : Important means of Important means of sustaining & spreading an outbreaksustaining & spreading an outbreakEnvironment-to-PersonEnvironment-to-Person: : Important Important means of sustaining & spreading an means of sustaining & spreading an outbreakoutbreak

Environment-to-Person &Environment-to-Person & Person-to-Person Person-to-Person

Norovirus TransmissionNorovirus Transmission

Contaminated surfaces are the most likely Contaminated surfaces are the most likely factor responsible for factor responsible for sustainingsustaining a a succession of outbreaks succession of outbreaks

Hands play a significant roleHands play a significant role in NoV in NoV transmission, either through direct fecal-transmission, either through direct fecal-oral contact, or through the contamination oral contact, or through the contamination of ready-to-eat food itemsof ready-to-eat food items

NoV Survival on HandsNoV Survival on Hands

If = to HAV: about 4 hrsIf = to HAV: about 4 hrs

Studies have shown at least 20 minutesStudies have shown at least 20 minutes

20 min – 4 hrs : survival rate on Hands20 min – 4 hrs : survival rate on Hands

Hand contaminationHand contaminationDe Wit, et al. 1992De Wit, et al. 1992

Examined the fecal contamination level Examined the fecal contamination level of the hands, after handwashing (of the hands, after handwashing (E.coliE.coli as an indicator).as an indicator).

Found Found E.coliE.coli in 25% of sampled individuals in 25% of sampled individuals after stoolsafter stools

Hand Contamination—De Wit’s Hand Contamination—De Wit’s studies Continuedstudies Continued

Handwashing decreased the E.coli Handwashing decreased the E.coli counts on the hands, but did not eliminate counts on the hands, but did not eliminate it.it.

Concluded that infected individuals Concluded that infected individuals shedding at high levels will have high shedding at high levels will have high hand contamination levels, even with hand contamination levels, even with hygiene practiced.hygiene practiced.

Hand TransmissionHand TransmissionHand contamination study: Hand contamination study:

14 out of 14 people contaminated by 14 out of 14 people contaminated by touching the same door handle, one after touching the same door handle, one after the otherthe other

13 out of 14 people contaminated by 13 out of 14 people contaminated by shaking hands with one contaminated shaking hands with one contaminated hand one after anotherhand one after another

Shaking hands with 1 contaminated Shaking hands with 1 contaminated person contaminated 6 other people.person contaminated 6 other people.

Hand TransmissionHand Transmission

1 door handle of an apartment shared by 4 students was 1 door handle of an apartment shared by 4 students was intentionally contaminated: intentionally contaminated: Spread throughout room---all surfaces tested. Contamination found Spread throughout room---all surfaces tested. Contamination found on all hands even after handwashing within 6 hrs.on all hands even after handwashing within 6 hrs.

Telephone in living roomTelephone in living room Drawer handles in kitchen and bathroomDrawer handles in kitchen and bathroom Water faucet in kitchen and bathroomWater faucet in kitchen and bathroom Light switch in kitchenLight switch in kitchen Refrigerator handle in kitchenRefrigerator handle in kitchen Bar of SoapBar of Soap Teapot HandleTeapot Handle

Transfer from Contaminated Transfer from Contaminated FingersFingers

Barker (2004) found that NoV can transfer from Barker (2004) found that NoV can transfer from contaminated fingers, sequentially to 7 different contaminated fingers, sequentially to 7 different environmental surfacesenvironmental surfaces

Secondary Transfer of NoV (from contaminated Secondary Transfer of NoV (from contaminated surfaces to clean fingers, to other surfaces) surfaces to clean fingers, to other surfaces) can transfer sequentially to 4 different surfacescan transfer sequentially to 4 different surfaces

Detergent cleaning, followed by rinsing was not Detergent cleaning, followed by rinsing was not effective in cleaning contaminated surfaces, unless effective in cleaning contaminated surfaces, unless followed with a disinfectant.followed with a disinfectant.

NoV Potential SourcesNoV Potential Sources

Contaminated SoilContaminated SoilFlood WatersFlood Waters

On Site Disposal SystemsOn Site Disposal Systems Septic TanksSeptic Tanks

Estimated that 40% are not functioning properlyEstimated that 40% are not functioning properly

NoV Survival in SoilNoV Survival in SoilAt least At least 12 weeks12 weeks were required for a 99% were required for a 99% reduction of HAV in soil at 41°F or 5°C.reduction of HAV in soil at 41°F or 5°C.

Reported viral decay Reported viral decay Winter field conditions ofWinter field conditions of 59°F59°F or or 15°C15°C

(moisture levels of 25-15%): (moisture levels of 25-15%): 92 days92 days Summer field conditions of 27-33°CSummer field conditions of 27-33°C or or 80.6 – 80.6 –

91.4°F91.4°F (moisture levels of 3-40%): (moisture levels of 3-40%): 1.2 days1.2 days

NoV Stability/Survival in WaterNoV Stability/Survival in Water

Survives freezing conditionsSurvives freezing conditionsSurvives exposure to acidity levels below pH 3Survives exposure to acidity levels below pH 3Presence of feces and viral aggregation prolongs NoV Presence of feces and viral aggregation prolongs NoV survivalsurvivalSurvives in Salt water (0.5 and 1 M NaCl) for Survives in Salt water (0.5 and 1 M NaCl) for >6 days at >6 days at room temperature (75.2°F)room temperature (75.2°F) Survives in dechlorinated water for Survives in dechlorinated water for 25 days at 39.2°F25 days at 39.2°F and for and for 18 days at 77°F18 days at 77°FInactivated by boiling at 212ºF Inactivated by boiling at 212ºF May survive up to 1 year in bottled drinking water stored May survive up to 1 year in bottled drinking water stored in the dark.in the dark.Impacted by microbial antagonism, sunlight, warmer Impacted by microbial antagonism, sunlight, warmer temperature and the presence of oxygentemperature and the presence of oxygen

NoV Stability/Survival in Food NoV Stability/Survival in Food

Survives freezing conditionsSurvives freezing conditionsSurvives heating at 140°F/ 60 ºC for 30 minutes—Survives heating at 140°F/ 60 ºC for 30 minutes—Inactivated by boiling at 212°F/ 100 ºCInactivated by boiling at 212°F/ 100 ºCImpacted by warmer temperature, sunlight, and Impacted by warmer temperature, sunlight, and oxygenoxygenSurvives exposure to acidity levels below pH 3Survives exposure to acidity levels below pH 3Survives better under wet conditions than dry Survives better under wet conditions than dry conditionsconditionsSurvives on produce longer than the shelf life of Survives on produce longer than the shelf life of the produce item under refrigerated temperatures.the produce item under refrigerated temperatures. May be susceptible to high pressure processingMay be susceptible to high pressure processing

NoV Survival on Hard SurfacesNoV Survival on Hard Surfaces

NoV Survival on Hard SurfacesNoV Survival on Hard Surfaces

Surface Surface Temp.Temp.

39.2°F39.2°F 71.6°F71.6°F 86°F86°F

NoV Survival NoV Survival Time Time

7 days7 days 5 days5 days < 24 < 24 hrshrs

•Presence of feces and viral aggregation on surfaces prolongs NoV survival

What does NoV like?What does NoV like?

Cool Cool

DarkDark

MoistMoist

Anaerobic, although not necessaryAnaerobic, although not necessary

Conditions That Support NoV Conditions That Support NoV Survival on ProduceSurvival on Produce

CoolCoolDarkDarkMoistMoistAnaerobic (without Oxygen)Anaerobic (without Oxygen)

Storage under these conditions reduces viral decay and Storage under these conditions reduces viral decay and enhances survival rates enhances survival rates

43%43% outbreaks probably had some type of produce/fruit outbreaks probably had some type of produce/fruit involvmentinvolvmentRemember peak rate is in Winter??Remember peak rate is in Winter??

NoV Environmental ContaminationNoV Environmental ContaminationEnvironmental surface tests--Hotel outbreakEnvironmental surface tests--Hotel outbreak

((Cheeseborough, 2000)Cheeseborough, 2000)

SurfaceSurface # Pos.# Pos. % Pos% Pos

Carpets (known recent vomit)Carpets (known recent vomit) 5 of 85 of 8 62%62%

Carpets (no known recent vomit)Carpets (no known recent vomit) 9 of 129 of 12 75%75%

Toilet rims/seatsToilet rims/seats 8 of 118 of 11 73%73%

Toilet handles, taps, basins & surfacesToilet handles, taps, basins & surfaces 13 of 3913 of 39 39%39%

Horizontal surfaces below 1.5m (railings, Horizontal surfaces below 1.5m (railings, switches, table tops, counters, ‘phones)switches, table tops, counters, ‘phones)

11 of 2911 of 29 37%37%

Horizontal surf. (light fittings, switches, Horizontal surf. (light fittings, switches, wardrobe tops, counter tops) above 1.5mwardrobe tops, counter tops) above 1.5m

6 of 126 of 12 50%50%

Phones, door handles, etc.Phones, door handles, etc. 7 of 297 of 29 24%24%

Soft furnishings, cushions, curtains, ect.Soft furnishings, cushions, curtains, ect. 2 of 102 of 10 20%20%

TotalTotal 61 of 14461 of 144 42%42%

Interrupting Human Transmission Interrupting Human Transmission PathwayPathway

Control MeasuresControl MeasuresHandwashing & prohibiting bare hand contactHandwashing & prohibiting bare hand contact with with RTE food items is criticalRTE food items is criticalRemoving food workers with active vomiting and/or Removing food workers with active vomiting and/or diarrhea is criticaldiarrhea is criticalReducing airborne transmissionReducing airborne transmissionTreat as infectious materialTreat as infectious materialCleaning Staff should use barriers, such as face masks, Cleaning Staff should use barriers, such as face masks, gloves, and aprons.gloves, and aprons.Dispose materials used to clean-up vomiting incident, Dispose materials used to clean-up vomiting incident, and thoroughly disinfect the area.and thoroughly disinfect the area.Properly disinfect contaminated environmentalProperly disinfect contaminated environmental surfacessurfaces

Restrooms are ReservoirsRestrooms are ReservoirsWash and dry produceWash and dry produce as much as possible, without direct as much as possible, without direct human contact, & avoid dark, anaerobic storage conditionshuman contact, & avoid dark, anaerobic storage conditions

Effective Disinfectants for NoV

Disinfectant Conc./ Contact Time

Surface/Product Reference

HypochlorousAcid solution(85-98% HOCl)

188ppm/ 1 min. Stainless steel; ceramic tiles

Park et al., 2007

SodiumHypochlorate from 5.25% Bleach Soln.

5000ppm/ 1 min. (25

tablespoons of household bleach [5.25%] per gallon of water)

Melamine (plastics) Barker, 2003

UV For FCV: 254 nm UV @ 19.04 mW s cm-2 or For MS2: 254 nm UV @ 62.50 mW s cm-2

Waste Water: secondary effluent

Tree, et al., 2005

High hydrostatic pressure

400-MPa at 5°C Oysters Kingsley et al., 2007

Heat 158°F/ 5 min., or 212°F/ 1 min.

Carpet; upholstered furniture

MIDCH, 2007

Ozone gas 0.37mg/l/ 10 sec. Contaminated water

Shin and Sobsey, 2003

20-25 ppm/ 20 min.

Office; hotel room; cruise ship settings

Hudson et al., 2007

Soap & WaterHandwash

1ml bland ivory soap/ 20 sec.

Hands Bidawid et al., 2004

Disinfectant Conc./ Contact Time

Surface/Product Reference

Effective Treatments Against NV Continued:

Points of ConcernPoints of Concern

Quaternary Ammonia is not effective on non-Quaternary Ammonia is not effective on non-enveloped viruses such as NoVenveloped viruses such as NoVHand Sanitizers (alcohol based) are NOT Hand Sanitizers (alcohol based) are NOT effective on NoV---Does kill Flu viruseffective on NoV---Does kill Flu virusContain as much of the “mess” as possible—Contain as much of the “mess” as possible—don’t spread moredon’t spread moreMUST DISINFECT APPROPRIATELY!!!MUST DISINFECT APPROPRIATELY!!!If a food contact surface: follow disinfectant with If a food contact surface: follow disinfectant with a potable water rinse after air drying to make the a potable water rinse after air drying to make the are safe for food contact again.are safe for food contact again.

ConclusionConclusion

Understanding the survival and Understanding the survival and transmission of NoV outside of the host transmission of NoV outside of the host

can help us develop effective control can help us develop effective control mechanismsmechanisms